JPS58173378A - Automatic opening type closing tool for casting crucible - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a self-opening closure for a thermite reaction casting crucible made of an inorganic refractory material which can be mechanically loaded and which does not generate gas when heated.

Thermite reactions are usually carried out in conical crucibles, with an outlet nozzle exchangeably arranged in the tapered lower section of the crucible. The outlet nozzle must be closed while the thermite reaction is in progress.

The metal melt generated during the thermite reaction is formed when the melt dross, which mostly consists of argunium oxide, separates from the metal melt and becomes suspended on the melt. For the first time, it can flow out from the outlet nozzle. If the outlet nozzle is opened too early, there is a risk that the casting will fail, either because the reaction of the thermite mixture is still incomplete or because the aluminum oxide dross formed is not completely separated from the metal melt. .

Opening of the outlet nozzle closure can be done mechanically or automatically.

When tapping is done mechanically, the welding operator looks into the crucible and measures when the dross has completely separated from the metal melt and is suspended in the exit nozzle. , pull upwards the spike-shaped closure bottle that acts as a seal. Regarding this technical stage, German patent specification 2
No. 230430. In the case of this type of tapping of molten metal, the correct choice of the point of opening of the outlet nozzle depends on the experience and skill of the operator. Do not drain the water too early for the reasons mentioned above. But also, don't be too late. This is because the temperature of the metal melt begins to drop again.

In order to increase the reliability of the welding, embodiments are also known in which the closure of the outlet nozzle is completely melted within a predetermined time by the metal melt due to thermite reaction. Already in 1902, a brochure from Aldemeine Chirsut (Erasen) contained a description of a self-opening closure for casting crucibles. In this case, the opening of the crucible is closed by a small asbestos disc about 50 m thick, topped by a small iron disc 3 mm thick and 3011 Im in diameter. A positive closure is achieved by placing an asbestos small disc under the iron small disc.The molten thermite iron completely dissolves the iron small disc and the asbestos small disc. The point at which the thickness is completely dissolved coincides with the point at which the iron platelet above it is completely dissolved.

This principle of construction of self-opening closures remains virtually unchanged today. In the case of German Patent Specification No. 2428770, a solid tablet with good mechanical resistance and no gas evolution when heated, with a thermal conductivity of 0.55
50ax/m sK, melting temperature from 1573 to 1873
Tadelet having a temperature in the range of K (=1300°C to 1600°C) is used as an automatic opening/closing device for the outlet of a fusion welding crucible using the Chill-Shito method. In this case, Tadelet contains 98% of Canada's Lysotil* fibrous asbestos.
Contains ~99-, and also has a thickness of 81.04 and a pull H'1
It is considered advantageous to use an asbestos board with a strength of 0.7 hf/ll, a melting temperature of 1725K, and a melt loss of about 1596. Thus, also in the case of DE 24 28 770, the crucible-mouth closing device is based on the asbestos board known since the beginning of this century. 0.555 above
The thermal conductivity upper limit of Ca17m- section is not an additional selection criterion. This is because all inorganic materials for damming have a thermal conductivity lower than that of O. Melting temperature 1573~1873K (=1300℃
˜1600° C.) is consistent with the m1ne range of asbestos, which has been used as a sealing material since the inception of thermite welding.

However, the automatic opening/closing device described in Patent Specification No. 12428770 is not fully satisfactory for several reasons.

One reason for this is that asbestos is not used as a sealing material in a manner consistent with the current state of the art. The health risks during the manufacture and use of seal discs, particularly when combined with the high temperatures of thermite reactions, are well known.

Another disadvantage of the seal disc under load is that
This is the point where the melting range is relatively low. For this, approximately 2500
There is a risk that the sealing disc will completely melt too quickly for metal melts at . In addition, modern welding methods, especially in the case of full fusion welding of rails, tend to carry out thermite reactions at even higher temperatures.

A further disadvantage is that the asbestos disk is in direct contact with the reacting thermite mixture. During the reaction of the thermite mixtures, strong currents, for example convection currents, are formed in the mixture, which convection leads to violent boiling of the liquid mixture, especially during the reaction. The sealed asbestos disk is therefore exposed not only to thermal stress, but also to mechanical stress due to heavy flow, which prevents parts of the disk from being physically stripped or washed away. First, this results in a reduction in the time until opening of the closure device.

The problem underlying the invention is that the opening time of the outlet can be easily predetermined and that time can be observed any number of times, and that the sealing material does not endanger the health of the welding workers. To provide an automatic opening/closing device without According to the invention, the above-mentioned drawbacks of the automatic opening and closing device are eliminated and, moreover, the solution III
J & Ri are not expensive either.

According to the present invention, this problem has been solved as follows. That is, the self-opening/closing device consists of one or more sealing discs 2 made of fibrous aluminum silicate, the ratio of the total thickness of the sealing discs 20 to the diameter being between 1:5 and 1=1. ★, the melting point of aluminum silicate is 21650℃, and on the Nur fist disk 2, 0
．． Metal plates 1 having a thickness of 1 wz to 6 kat were arranged.

An important aspect of this closure is the material used for the seal. The material used is fibrous aluminum silicate, and this aluminum silicate is what makes Cerakentsu! It is hardened into a fleece-like or paper-like material using a binder. As in multilayer paper production, the intertwined layers of K, aluminum silicate are bonded together, resulting in a cardboard-like product of any given thickness. This material is commercially available, but commercially available products have varying melting points. In the case of the present invention, a material with a melting point of 21650° C. is used. Particularly advantageous is the melting point of 1
The temperature is 700°C±20°C.

Materials of this kind are, for example, Nefax
it) 16' (manufacturer is B, V, N5f
It is commercially available under the trade name of ABAS.

The thickness of the seal disc has a specific ratio to the diameter of the disc. ! #Ratio of diameter to 1:5 to 1
: The range is 1. This results in a minimum thickness of 4 mm for a disk diameter of 20 m. The opening time of the closure device can be controlled by selecting the thickness of the sealing disc. Also, the thickness of the sealing disk can be adapted to the heat of reaction of the chillite mixture used with it. In that case, it has proven to be particularly advantageous to, instead of using a single disk of the desired thickness, to superpose several disks of corresponding thickness so that the total thickness is a given lumen. . Surprisingly, it has been found that such multiple discs provide better reproducibility of tapping time than a single disc.

On top of this disc or discs is placed a metal plate, which, at the current level of technology, no longer has a mechanical support function, but is simply placed on the top It merely serves to prevent the sealing disc from being mechanically damaged by boiling-up reactants.

This metal plate has two functions. That is, in the negative side, the upper surface of the upper sealing disk is removed from the mechanical load;
On the other hand, the heat acting on the sealing disc is distributed evenly over the entire surface of the sealing disc due to the high thermal conductivity. This is important because the reaction starts at one point and spreads through the entire reaction mixture, so local overheating can occur at the beginning of the reaction. Needless to say, the metal plate will melt into the metal melt during the progress of the thermite reaction. However, as mentioned above, sufficient time is allowed for the melting of the gold X plate in order to protect the seal O disk below.

The metal plate usually consists of iron or steel. However, it may also consist of lighter metals, such as aluminum or ram. However, in that case, it is necessary to perform appropriate mechanical fixation to prevent the metal plate from lifting up. In many cases, it has proven advantageous for the metal plate to be made of, for example, an iron-manganese alloy or an iron-chromium alloy. This greatly simplifies the incorporation of metal additives which influence the properties into the metal produced by the Chirsat reaction.

In one advantageous embodiment of the invention, a self-opening closure is arranged in the outlet passage of a replaceable outlet nozzle inserted into the casting collar. A self-opening closure consisting of one or more sealing disks and a metal plate placed on the disks can then be inserted into a corresponding recess of the outlet nozzle. The closure, which consists of several individual parts, can also be covered with a metal or plastic sheet to allow for loose packaging and handling.

According to another advantageous embodiment of the invention, the self-opening closure is arranged in the lower region of the sleeve, which sleeve is designed to be inserted into the outlet nozzle. This sleeve can be filled with thermite reactant in a manner known per se. In that case, the sleeve end projecting into the crucible can be either open or closed, as is the case, for example, in DE 24 28 770.

An embodiment of the self-opening closure according to the invention will now be described with reference to the accompanying drawings: In FIG. A conical outlet nozzle 4 is fitted into the casting crucible 5, and an outlet passage 7 is formed in the center of the nozzle 4. An annular cutout is formed in the upper area of the outlet nozzle 4. The sealing discs 2 and 3 rest on the annular shoulder formed by this recess.

A metal plate 1 is arranged above the upper sealing disc 2.

In FIG. 2, reference numeral 5 designates the casting crucible and 4 designates the outlet nozzle. A sleeve 6 is fitted into the corresponding recess of the outlet nozzle 4, which sleeve 6 is preferably provided with a floor with a central opening 8. On this annular floor are sealing discs 2.
2' and 3 are placed. A metal plate 1 is mounted on these seal disks. In order to prevent the disk from falling off, the sleeve 6 is formed with an annular groove just above the metal plate 1. The free space in the sleeve 6 above the metal plate 1 can be filled with a thermite mixture. In that case, it is recommended to close the sleeve 6 with a lid or crush the sleeve 6.

In order to protect the outlet nozzle 4, after inserting the sleeve 6, the space formed by the outer wall of the sleeve 6, the inner wall of the crucible 5, the floor of the casting crucible 5 or the upper surface of the outlet sleeve 4 is filled with sand, for example slag sand. It can also be filled with.

[Brief explanation of the drawing]

1 and 2 are vertical cross-sectional views taken through the center of the lower region of the casting collar. In the diagram: 1...Metal plate 2.3...Seal disc 4...Outlet nozzle 5...Lower crucible area 6...Sleeve 7...Exit passage representative Asamura Kogai 4 people

Claims (3)

[Claims] (1) A self-fogging closure for casting crucibles used in thermite reactions, which is made of an inorganic refractory material that can be subjected to mechanical loads and does not generate gas upon heating, the closure being - It consists of one or more seal Φ discs (2) made of aluminum silicate, and the ratio of the total thickness of the seal disc (2) to the diameter is between 1=5 and 1:1. The melting point of aluminum silicate is 21,650°C, and the metal plate (1) with a thickness of 0.1 m to 3 mm is placed on the sealing disc (2). A self-opening closure for casting crucibles. (2) The closing fs device is arranged in the outlet n1l (7) of the replaceable outlet nozzle (4) inserted in the casting collar (5). Closures as described in section. (3) A closure device is arranged in the lower region of the sleeve (6), which sleeve (6) is configured to be insertable into the outlet nozzle (4). Closure device according to paragraph 1.